<!DOCTYPE html>
<html lang="en">

<head>
    <title>html5</title>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1"> </head>

<body>
    <form action="demo-form.php" id="form1"> First name:
        <input type="text" name="fname">
        <br>
        <input type="submit" value="提交">
    </form>
    Last name:
    <input type="text" name="lname" form="form1"> </body>

</html>